US4382864A - Process for dewatering sludges - Google Patents
Process for dewatering sludges Download PDFInfo
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- US4382864A US4382864A US06/287,453 US28745381A US4382864A US 4382864 A US4382864 A US 4382864A US 28745381 A US28745381 A US 28745381A US 4382864 A US4382864 A US 4382864A
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- sludge
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5263—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using natural chemical compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
Definitions
- the present invention relates to a process for dewatering sludges, especially for dewatering sewage sludges by the formation of flocs caused by addition of flocculant to the sludges.
- This prior process thus consists in first forming a primary floc by neutralizing the electric charge of the sludge by addition of a first high molecular weight flocculant, and then causing formation of giant flocs by addition of a second high molecular weight flocculant, before carrying out the dewatering operation.
- This process attains a better dewatering performance due to the formation of giant stout flocs, even for a sludge that will merely form small and feeble flocs upon addition of either an anionic or cationic high molecular weight flocculant only.
- This prior process exhibits, however, narrow permissible ranges for the amounts of addition of both the cationic and anionic high molecular weight flocculants, in addition to a narrow permissible range of the dosage ratio between both flocculants, so that regulation and control in practical applications where the variations in the concentration and properties of the sludge are considerable, are substantially difficult.
- the process shows a further shortcoming in that, although the flocs formed are large and stout, they form a tenacious dewatered cake and in addition, the moisture content of the dewatered cake from this process is high as compared with that of a cake obtained by the sole addition of a cationic or anionic flocculant, so that the filtration velocity is decreased.
- Another object of the present invention is to provide a process for dewatering sludges in which efficient dewatering can be realized by formation of flocs showing better dewatering ability, so as to lower the moisture content of the dewatered cake.
- Still another object of the present invention is to provide a process for dewatering sludges in which the amount of suspended solids removed can be increased.
- a further object of the present invention is to provide a process for dewatering sludges in which efficient press filtration under a high squeezing pressure can be achieved.
- a still further object of the present invention is to provide a process for dewatering sludges in which the bulk volume of the dewatered cake can be decreased.
- Another object of the present invention is to provide a process for dewatering sludges in such an energy efficient manner that the amount of supplemental fuel needed for combustion of the dewatered cake is decreased.
- the process for dewatering sludges comprises conducting a first stage dewatering comprising agitating of the sludge to be dewatered while adding a first high molecular weight flocculant that develops on an aqueous solution an electric charge of polarity opposite to that of said sludge, performing subsequently a second stage dewatering comprising agitating the sludge while adding a second high molecular weight flocculant develops in an aqueous solution an electric charge of polarity opposite to that of said first flocculant, and thereafter subjecting the flocs thus formed to a dewatering operation, wherein at least one of said first and second flocculants is a flocculant consisting of a natural high molecular weight organic compound or a derivative thereof.
- the first stage agitation of the process according to the present invention is performed preferably with a stronger agitation intensity than that employed in conventional flocculation in sewage work, while the second stage agitation may be carried out in an ordinary manner.
- centrifugation, vacuum filtration and press filtration can be employed, but it is not preferable to employ, press filtration with a filter cloth under pressure of at least 1 kg/cm 2 .
- sludges containing relatively large amounts of metal hydroxides such as Alum coagulation sludge and inorganic sludges, exist in general in a cationic state.
- the ionic polarity of such sludges may be determined using, for example, a zeta meter.
- the first high molecular weight flocculant (referred to hereinafter as flocculant I) to be added initially to the sludge to be dewatered is one which will develop an electric charge in an aqueous solution of polarity opposite to that of the sludge.
- a flocculant of cationic nature is added to an anionic sludge and vice versa.
- the second high molecular weight flocculant (hereinafter referred to as flocculant II) has an electric charge in an aqueous solution of polarity opposite to that of flocculant I, so that an anionic flocculant is employed as flocculant II when using a flocculant I of a cationic nature has been used in the first stage, and vice versa.
- At least one of said flocculants I and II should be a flocculant consisting of a natural high molecular weight organic compound or a derivative of such a compound.
- Examples of such natural high molecular weight organic compounds and derivatives thereof include, as those of anionic nature, carboxymethyl cellulose, sodium alginate and carboxymethyl starch, and as those of cationic nature, cationized starch, cationized cellulose, cationized guar gum and chitosan.
- These natural high molecular organic compounds and derivatives thereof can be used either for the flocculant I or for the flocculant II in the process according to the present invention. It is also permissible to use such natural high molecular organic compounds and derivatives thereof for both the flocculants I and II. If a natural high molecular organic compound or a derivative thereof is used for one of the flocculants I and II, a synthetic high molecular weight flocculant can be used for the other one. It is possible also to use such a natural high molecular compound in a mixture with a synthetic high molecular weight flocculant.
- the synthetic high molecular weight flocculants which can be used in the process according to the present invention
- those which have conventionally been employed can be used, such as polyacrylic acid and salts thereof, partially hydrolyzed polyacrylamide, and so on for those of anionic nature and, for example, homopolymers of aminoalkyl (meth)acrylates and copolymers thereof with other monomers, Mannich-reaction polyacrylamide, Hofmann-degradated products of polyacrylamide, polyamidepolyamines, polyvinyl imidazoline, polyethyleneimine, salts of polydialkyldiallylammonium, and so on for those of cationic nature.
- Such synthetic flocculants can be used either alone or in a mixture of two or more of them.
- carboxymethyl cellulose and chitosan have been shown to be highly effective and, in particular, chitosan is most preferable.
- chitosan as the natural high molecular organic compound, it is particularly effective to employ polyacrylic acid or a salt thereof as the other high molecular weight flocculant of anionic nature.
- Chitosan can be obtained from the cuticle of crustaceans such as crab, lobster and so on by deacetylation. While chitosan in itself is insoluble in water, it can be rendered water-soluble by converting it into a salt of an organic or inorganic acid (excluding sulfuric acid). Therefore, chitosan is used in the process according to the present invention in the form of a water-soluble salt of an organic or inorganic acid. Examples of water-soluble inorganic and organic acid salts of chitosan are formate, acetate, hydrochloride, nitrate and so on.
- a water-soluble salt of chitosan per se can be admixed to the sludge, but it is preferable, for the sake of easy handling and prompt and homogeneous distribution over the entire bulk of the sludge, to use it in a form of an aqueous solution.
- polyacrylates polyacrylic acid, sodium polyacrylate, potassium polyacrylate and so on can be employed, preferably in a form of aqueous solution in the same manner as chitosan.
- polyacrylic acid and salts thereof conventional products used hitherto as flocculants may be employed, which may have an intrinsic viscosity of about 1-15 [dl/g] determined at 30° C. using 2N-aqueous solution of sodium hydroxide as solvent.
- the dosages of the high molecular weight flocculants may vary according to the properties of the sludge, such as the pH value, content of suspended solids (hereinafter abbreviated as SS), content of volatile suspended solids (abbreviated hereinafter as VSS), electric conductivity and so on, a dosage of about 0.2-3% by weight, based on the amount of SS, for an organic high molecular weight flocculant of anionic nature and a dosage of about 0.5-6% by weight, based on the amount of SS, for an organic high molecular weight flocculant of cationic nature may generally be adopted.
- SS content of suspended solids
- VSS volatile suspended solids
- electric conductivity so on
- the sludge to be dewatered is treated such that, first, the flocculant I is added to the sludge and the sludge is subjected to the first stage agitation so as to neutralize the ionic charge of the sludge, and then the flocculant II is added thereto and the sludge is subjected to the second stage agitation so as to cause flocculation of the sludge. While it is permissible, to carry out the first stage agitation with an ordinary agitation strength, i.e.
- the second stage agitation can be performed at an ordinary strength.
- the strength of agitation in the first stage agitation is preferably chosen so that no flocculation occurs or only flocs having floc sizes not greater than 2 mm will be formed, whereby the electric charge of the sludge can be neutralized.
- the flocs remain internally still in an unreacted state with the electric charge not yet neutralized, retaining a large amount of moisture, so that the internal moisture of the flocs is difficult to remove by squeezing or the like.
- the fact that there was no marked difference in the dewatering ability between the sludge obtained by the two-stage flocculation technique and the sludge obtained by the single stage flocculation may be attributed to the above reason.
- the electric charge of the sludge is neutralized internally by employing a powerful agitation in the first stage after the addition of the flocculant I, so that the dewatering performance can considerably be increased by the second flocculation effected by the addition of the flocculant II.
- the flocculant II is added thereto and the second stage agitation is performed so as to cause flocculation to occur.
- the condition of agitation may be the ordinary agitation required for causing flocculation.
- the flocculant I is introduced in the suction side of the pump that transports the sludge into the dewatering device to thereby attain an intense agitation by the pump so as to effect a thorough reaction over the entire bulk of the sludge to neutralize the electric charge of the sludge.
- the addition of the flocculant II makes it possible to form a floc with improved dewatering performance.
- the flocculated sludge formed through the use of a natural high molecular organic compound or its derivative as at least one of the flocculants I and II is large in size and shows a low tenacity with an unsticky dry touch, so that it also exhibits low adhesive property to the filter cloth, resulting in an excellent dewatering performance upon filtration.
- the flocculated sludge obtained by the use of synthetic high molecular weight flocculant for both the flocculants I and II is very tenacious, with higher adhesion onto the filter cloth, resulting in a dewatering performance which is inferior as compared with the former flocculated sludge.
- the floc formed by using chitosan, polyethyleneimine and so on for the flocculant I will have a smaller size and the flocculating function becomes worse.
- the flocculating function is improved when an alkaline earth compound, such as chloride, nitrate and so on (excluding sulfate) or hydroxide of calcium, magnesium or barium, is added to the sludge.
- the amount of alkaline earth compound added should be at least 0.2 equivalent with respect to the sulfate ion and preferably about 1 equivalent or more.
- the flocculation is achieved either in a manner such that the alkaline earth compound is added to the sulfate-containing suspension and agitation is carried out before the addition of the flocculants, or in a way such that the alkaline earth compound is added at the same time as the flocculant and subsequently agitation is conducted to attain flocculation. It is permissible to add the alkaline earth compound and the flocculant either separately or simultaneously in a form of a mixture.
- the alkaline earth compounds exemplified above can be used alone or in combinations of them.
- the thus-formed floc is transferred as is, or after the removal of the separated water, to a dewatering device to effect dewatering in a known manner.
- a dewatering device for practical dewatering, centrifugation, vacuum filtration and squeezing may be employed.
- the dewatering device to effect these dewatering techniques those which have already been adopted can be employed, such as, for example, a centrifuge, a vacuum filter, a dehydrator of the belt press type, a screw press and a filter press.
- a squeezing pressure of more than 1 kg/cm 2 can be achieved by the process according to the present invention, in contrast to the prior process in which a squeezing pressure of more than 0.5 kg/cm 2 has never been used owing to the poor exfoliative property of the retained cake to the filter cloth, and due to the possible protrusion of the cake from the filter cloth edges.
- a dewatered cake having a low moisture content which is dependent on the squeezing pressure, can be obtained.
- the flocculated sludge may be supplied as is or after the removal of the separated water layer to a squeezing dehydrator having a filter cloth to effect dewatering, by squeezing under a pressure of 1 kg/cm 2 or more. While there is no restriction as to the construction of the squeezing dehydrator, it may be preferable to employ a squeezing dehydrator of the belt press type, in which two sheets of filter cloth each having the form of endless belt are moved in parallel while the sludge to be dewatered is held therebetween and the cloths are pressed from the outside by rollers.
- the squeezing pressure in a belt press type squeezing dehydrator having two travelling filter cloths supported on rollers can be calculated by the equation:
- F represents the tensile force (kg/cm) of the filter cloth
- r indicates the radius (cm) of the roller
- d denotes the thickness (cm) of the cake
- L 1 is the width (cm) of the filter cloth
- L 2 is the width (cm) of the cake.
- the dewatered cake obtained by the process according to the present invention is then disposed of by, for example, incineration or composting. Due to its low moisture content, it offers the advantages that the amount of supplementary fuel needed for the incineration can be minimized and that the additives for regulating the moisture content in the composting can be spared.
- the sludge dewatering process according to the present invention offers many advantages, for example:
- a flocculant selected from the group of flocculants II also recited in Table I was added to the sludge and the second stage agitation was effected as stated in Table I.
- the sludge thus flocculated was poured in a Buchner funnel covered with a 100-mesh nylon filter cloth and the volume of filtrate collected in 20 seconds was determined (Nutsche test). 15 g of the thus-filtered sludge (filter cake) were placed between a filter cloth to be used for belt press filtration and a layer of a sponge, to effect squeezing under a pressure of 0.5 kg/cm 2 for two minutes (press test). The cake after this press test was examined for its moisture content.
- the intense agitation was carried out using a handmixer having two beaters such, that the mixer was operated at a rate of revolution of 500 rpm for 30 seconds, whereas the ordinary agitation was performed using a handmixer having only one beater operating at a rate of revolution of 250 rpm for 20 seconds.
- a similar test was carried out wherein flocculants I only were used.
- Results obtained are shown in FIG. 1, in which the numerals beside each plot point represent the floc size in mm.
- the volume of filtrate collected in 20 seconds for the test No. Ib was observed to be lower than 10 ml and that for the test No. IIb was recognized to be lower than 20 ml.
- Example 3 Using the sludge employed in Example 1 and flocculants given in Table IV, press tests were carried out with varying agitation conditions as given in Table IV, otherwise under the same condition as in Example 1 at various squeezing pressures.
- the dewatered cakes in the region beyond the right hand ends of the curves IVa and IVb of FIG. 3 could not be subjected to the squeezing dewatering operation, due to the insufficient strength of the dewatered cake and due to the inferior exfoliative aspect of the cake.
- the process according to the present invention provides a treatment which is stable and which exhibits a wide range of allowable dosages of the flocculant I with simultaneous attainment of better filtrability and lower moisture content of the dewatered cake as compared with those obtained according to Va and Vb.
- An alum coagulation sludge having a content of SS of 3.49% with VSS proportion of 75.1%, based on the weight of SS, a pH of 6.2 and an electric conductivity of 2,580 ⁇ S/cm, from paper and pulp mill waste water was treated by flocculation under the conditions given in Table VI and the so flocculated sludge was then subjected to the Nutsche test and press test under the same conditions as in Example 1.
- Example 7 The procedures of Example 7 were followed with the exception that the dosages of anionic and cationic high molecular weight flocculants were changed to 75 mg/l and 200 mg/l respectively, to carry out press tests under various squeezing pressures.
- Example 7 sodium polyacrylate as employed in Example 7 was added to the mixture as the flocculant II and the second stage agitation at ordinary intensity was carried out using a hand mixer having only one beater at 250 rpm (corresponding to a circumferential velocity of 0.5 m/sec) for 15 seconds to effect flocculation.
- the so-obtained flocculated sludge was examined for floc size filtrability by pouring the sludge into a Buchner funnel covered with a 100-mesh nylon filter cloth to determine the volume of filtrate during certain time intervals.
- Table XIII together with the testing conditions. For comparison, test results for the cases in which an alkaline earth metal compound was not added and both alkaline earth metal compound as well as inorganic sulfate were not added are also given therein.
- Example 7 The NaPA used in Example 7 was added thereto and agitation of ordinary intensity was used to effect flocculation of the sludge.
- the flocculated sludge was examined by the Nutsche test and press test, the results of which are recited in Table XIV together with the testing conditions.
- Second stage agitation was then conducted after the addition of the flocculant II in an amount indicated in Table XV under agitation of ordinary intensity, by employing a hand-mixer having one beater at 250 rpm (corresponding to a circumferential velocity of 0.5 m/sec.) for 20 seconds.
- the flocculated sludge was poured into a Buchner funnel covered with a 100-mesh nylon filter cloth to conduct a Nutsche test by measuring the volume of filtrate collected in 20 seconds. 15 g of filtered sludge cake were then sampled.
- the flocculant CVI denoted in Table XVI was added as the flocculant I in an amount of 1.0% by weight, based on the SS content of the sludge.
- the first stage agitation was carried out in a reaction vessel with a detention time of 2 minutes by agitating the sludge at varying intensities.
- the rate of revolution of the stirrer within the range from 25 to 250 rpm (corresponding to the range of circumferential velocity from 0.5 to 5 m/sec.), changes in agitation intensity were achieved.
- the flocculant AI denoted in Table XVI was added as the flocculant II in an amount of 0.50% by weight, based on the SS content.
- the second agitation was carried out in a reaction vessel with detention time of 2 minutes at an ordinary agitation intensity of 25 rpm (corresponding to a circumferential velocity of 0.5 m/sec) of the stirrer.
- the flocculated sludge was supplied to a squeezing filtration dehydrator HYDOPRESS PA 1250 (trade mark of Kurita Water Industries Ltd.) of the belt press type having filter cloths to effect dewatering.
- the filter cloth was made of polyester woven in a herringbone pattern, exhibiting an air permeation rate of 16,000 ml/min/cm 2 and having a width of 125 cm.
- the dewatering was carried out at a filter cloth travelling velocity of 0.4 m/min and at a sludge dewatering rate of 60 kg of dry solids per meter of filter cloth width per hour under various squeezing pressures varied for each agitation intensity of the first stage agitation.
- the capture yield results of SS (suspended solids capture) and moisture content of the dewatered cake observed are shown in FIG. 12 in graphic illustration.
- a first flocculant selected from those given in Table XX an intense first stage agitation was effected at a rate of revolution of the impeller of 125 rpm (corresponding to a circumferential velocity of 2.5 m/sec).
- the mixture was conducted into a second agitation tank (detention time: 2 minutes) also equipped with an agitating impeller, in which the mixture was dosed with a second flocculant selected from those given in Table XX and was subjected to a second stage agitation of usual mild intensity realized by operating the impeller at a rate of revolution of 25 rpm (corresponding) to a circumferential velocity of 0.5 m/sec).
- the flocculated mixture was then transported into the belt press type dehydrator used in Example 16 to subject the mixture to dewatering.
- the travelling velocity of the filter cloth was adjusted at 0.93 m/min and the sludge dewatering rate was set at 100 kg of dried sludge per meter of filter cloth width per hour.
- the plot point C 4 represents the extreme limit of effective squeezing pressure taking into account the results of suspended solids capture and of exfoliation index.
- the plot point C 5 indicates that a further increase of squeezing pressure will never result in a substantial further improvement in the moisture content and in the exfoliative aspect as well.
- the moisture content of the dewatered cake can be decreased to a considerable measure, while the value for the suspended solids capture tends somewhat to decrease.
- the limit of effective squeezing pressure for the case (B) lies at the point B 5 (corresponding to the squeezing pressure of 2.5 kg/cm 2 ) and that for the case (A) at 7 kg/cm 2 .
- the agitation intensity in the first stage agitation was changed within the range of rate of revolution of impeller of from 25 rpm to 250 rpm (corresponding to the range of circumferential velocity of from 0.5 to 5 m/sec), so as to observe the influence upon the average size of the resulting floc after agitation.
- the size of the floc was determined by microscopic photograph. All other conditions were the same as in Example 17.
- the dewatering was performed at a travelling velocity of the filter cloth of 0.4 m/sec. and a sludge dewatering rate of 60 kg dry solids/m.hr, under pressure varied for each level of agitation intensity in the first stage agitation.
- the observed data for the suspended solids capture and for the moisture content of dewatered cake is given in FIG. 17 in graphic illustrations.
- a dewatering operation at a pressure over 1 kg/cm 2 is made possible when the first stage agitation is performed with high intensity so as not to form a floc having an average floc size greater than 2 mm (inclusive of the case in which no flocculation occurs) in order to cause substantial neutralization of the charge of sludge particles, whereby it is also possible to increase the sludge dewatering rate.
- said first flocculant was added in a first agitation tank disposed on the delivery side of the pump and equipped with an agitating impeller operated at a rate of revolution of 25 rpm (corresponding to a circumferential velocity of 0.5 m/sec.) to cause an ordinary mild agitation.
- Each flocculated sludge mixture was then supplied to the squeezing filtration dehydrator of belt press type as employed in Example 16, to effect dewatering.
- the dewatering was carried out at a filter cloth travelling velocity of 0.96 m/min., under a tension of the filter cloth of 7 kg/cm and at a sludge dewatering rate of 100 kg-dry solids/m.hr.
- Table XXVI The results of observations of the moisture content of dewatered cake and the yield of suspended solids capture are summarized in Table XXVI.
- As the first flocculant an anionic flocculant given in Table XXV and, as the second flocculant, a cationic flocculant given in Table XXV were employed.
- the sludge dewatering rate was set to 125 kg-dry solids/m.hr. Other conditions were the same as in Example 21. The results obtained are shown in Table XXVII.
- the floc size was smaller as compared with the case in which the first stage agitation was conducted in the first agitation tank, the latter resulting in an increase in the moisture content of the dewatered cake and a decrease in the yield of suspended solids capture. This effect was greater when a natural high molecular organic compound was employed.
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Abstract
Description
Squeezing Pressure (kg/cm.sup.2)=[F/(r+d)]×[L.sub.1 /L.sub.2 ],
TABLE I ______________________________________ 1st Stage 2nd Test Flocculants Agita- Flocculants Dosage Stage No. I* tion II* (mg/l) Agitation ______________________________________ I DAM 1.0intense CMC 150 ordinary Ia DAM 1.0ordinary CMC 150 ordinary Ib DAM 1.0 intense -- -- -- Ic DAM 1.0 ordinary -- -- -- II DAM 3.8intense CMC 150 ordinary IIa DAM 3.8ordinary CMC 150 ordinary IIb DAM 3.8 intense -- -- -- IIc DAM 3.8 ordinary -- -- -- ______________________________________ *See Table II
TABLE II __________________________________________________________________________ Description of the Flocculant Used Abbr. Compound CE-Value Viscosity Value __________________________________________________________________________ CTS Acetic acid salt of 4.2 meq/g 80 cP (0.5% aq. soln.) chitosan PEI Polyethyleneimine M.W. = 100,000 DAM 1.0 Homopolymer of dimethyl- 4.81 [η].sup.30° C. .sub.1N--NaCl = 1.0 aminoethyl methacrylate meq/g quaternized with methyl chloride DAM 2.7 Homopolymer of dimethyl- 4.81 [η].sup.30° C. .sub.1N--NaCl = 2.7 aminoethyl methacrylate meq/g quaternized with methyl chloride DAM 3.8 Homopolymer of dimethyl- 4.81 [η].sup.30° C. .sub.1N--NaCl = 3.8 aminoethyl methacrylate meq/g quaternized with methyl chloride DAM 5.0 Homopolymer of dimethyl- 4.81 [η].sup.30° C. .sub.1N--NaCl = 5.0 aminoethyl methacrylate meq/g quaternized with methyl chloride DAM/AAm 1:1 copolymer of 3.6 meq/g [η].sup.30° C. .sub.1N-- NaCl = 10.4 acrylamide and dimethylaminoethyl methacrylate quater- nized with methyl chloride DDA Homopolymer of di- 5.83 meq/g [η].sup.30° C. .sub.1N--NaCl = 1.2 methyldiallylammonium chloride CMC Carboxymethyl cellulose -3.21 [η].sup.30° C. .sub.1N--NaCl = 14.6 meq/g PAA Partially hydrolyzed -3.52 [η].sup.30° C. .sub.1N--NaCl = 13.3 13.3 product of polyacryl- meq/g amide PAA Partially hydrolyzed -3.82 [η].sup.30° C. .sub.1N--NaCl = 15.3 15.3 product of polyacryl- meq/g amide PAA Partially hydrolyzed -2.73 [η].sup.30° C. .sub.1N--NaCl = 17.5 17.5 product of polyacryl- meq/g amide __________________________________________________________________________
TABLE III ______________________________________ 1st 2nd Stage stage Test Dosage Agita- Agita- No. Flocculant I (mg/l) tion Flocculant II tion ______________________________________III PEI 600 intense CMCordinary IIIa PEI 600 intense PAA 17.5 ordinary ______________________________________
TABLE IV ______________________________________ 1st 2nd Dos- Stage Floccu- Stage Test Floccu- age Agita- lant Dosage Agita- No. lant I mg/l tion II mg/l tion ______________________________________IV PEI 600intense CMC 150ordinary IVa PEI 600 intense PAA 17.5 50 ordinary IVb DAM 3.8 300 ordinary -- -- -- ______________________________________
TABLE V ______________________________________ 1st 2nd Stage Stage Test Floccu- Agita- Floccu- Dosage Agita- No. lant I tion lant II (mg/l) tion ______________________________________ V DDAintense CMC 100 ordinary Va DDA intense PAA 13.3 65 ordinary Vb DAM/AAm ordinary -- -- -- ______________________________________
TABLE VI ______________________________________ 1st 2nd Stage Stage Test Floccu- Agita- Floccu- Dosage Agita- No. lant I tion lant II (mg/l) tion ______________________________________ VI PAA 15.3intense CTS 150 ordinary VIa PAA 15.3 intense DAM 2.7 150 ordinary VIb PAA 15.3 ordinary -- -- -- ______________________________________
TABLE VII ______________________________________ Volume Dos- 1st Floc- Dos- 2nd of Floc- age Stage cu- age Stage Filtrate Test cu- (mg/ Agita- lant (mg/ Agita- collected No. lant I l) tion II l) tion in 20 sec. ______________________________________ VII CTS 480intense PAA 50 ordinary 98 15.3VIIa DAM 200intense PAA 50 ordinary 60 5.0 15.3 ______________________________________
TABLE VIII ______________________________________ Pressure Moisture Cont. of Cake (wt. %) (kg/cm.sup.2) Test No. VII Test No. VIIa ______________________________________ 0.5 77.7 81.0 1.0 74.0 77.8 1.7 70.0 74 (poorly exfoliative) ______________________________________
TABLE IX ______________________________________ Volume of Filtrate Moisture Content Flocculant Dosage collected in 20 sec. of dewatered Used mg/l (ml) Cake (wt. %) ______________________________________ CTS *1 150 105 72.5 NaPA *2 75CTS 200 140 71.4 NaPA 75CTS 300 153 69.7 NaPA 75 DAM *3 150 84 76.0 NaPA 75DAM 200 94 75.0 NaPA 75DAM 300 117 73.6 NaPA 75CTS 150 88 74.1 PAAm *4 75CTS 200 105 73.2 PAAm 75CTS 300 127 72.6 PAAm 75 ______________________________________ *1 Acetic acid salt, with colloid equivalent of 4.2 meq/g: viscosity of 0.5% aqueous solution at 30° C. = 80 cP (with Btype viscometer at 30 rpm). *2 Sodium salt of polyacrylic acid, with [η ] .sup.30° C..sub.2N--NaOH = 6.6 [dl/g]- *3 Homopolymer of dimethylaminoethyl methacrylate quaternized with methyl chloride of 4.81 meq/g; [η].sup.30° C..sub.1N--NaCl = 5.0 [dl/g]- *4 Partially hydrolyzed polyacrylamide, with colloid equivalent of -3.82 meq/g; [η].sup.30° C..sub.1N--NaCl = 15.3 [dl/g]-
TABLE X ______________________________________ Moisture Content in Wt. % of Dewatered cake for Squeezing Pressure at: 0.5 1.0 3.0 5.0 Condition kg/cm.sup.2 kg/cm.sup.2 kg/cm.sup.2 kg/cm.sup.2 ______________________________________ A 71.4 69.0 64.8 63.0 B 73.2 71.3 67.5 -- C 76.5 -- -- -- ______________________________________
TABLE XI ______________________________________ Sludge Volume in Sedimentation Flocculant Dosage (Vol. % to initial Volume) used (mg/l) after 5 min. after 30 min. ______________________________________ CTS 0.20 84 40 NaPA 0.10 CTS 0.20 87 51 PAAm 0.10 DAM 0.20 89 56 NaPA 0.10 Blank -- 91 66 ______________________________________
TABLE XII ______________________________________ Volume of Filtrate Moisture Content Flocculant Dosage Collected in 20 sec. of Dewatered Used (mg/l) (ml) Cake (wt. %) ______________________________________NaPA 200 106 77.8CTS 150 NaPA 250 124 76.7CTS 150NaPA 300 133 76.1CTS 150PAAm 200 84 80.2CTS 150 PAAm 250 104 79.3CTS 150PAAm 300 115 79.2CTS 150NaPA 200 71 81.8DAM 150 NaPA 250 83 81.1DAM 150NaPA 300 90 80.7DAM 150NaPA 300 85 83.2 ______________________________________
TABLE XIII __________________________________________________________________________ Amount of Alkaline Volume of Filtrate collected (ml) Amount of Earth Com- Dosage of Dosage of Floc At specified Time Intervals Sulfate pound addedFlocculant Flocculant Diameter 10 20 30 45 60 added (N) (N) I (mg/l) II (mg/l) (mm) sec. sec. sec. sec. sec. __________________________________________________________________________ -- -- 250 75 2.0-3.0 97 117 133 146 157 (NaCl 0.1) -- 250 75 2.0-3.0 96 115 130 144 156 0.05 Na.sub.2 SO.sub.4 -- 250 75 0.7-1.0 62 81 96 113 125 0.1 0.3-0.5 15 20 23 27 31 MgSO.sub.4 0.05 -- 250 75 0.5-0.7 33 43 47 53 58 ZnSO.sub.4 0.05 -- 250 75 0.3-0.5 13 17 21 27 29 0.01 75 1.5-2.0 85 103 118 134 148 Na.sub.2 SO.sub.4 0.05 CaCl.sub.2 0.02 250 75 1.5-2.0 93 115 129 146 155 0.05 150 1.0-1.5 98 118 134 149 160 0.01 1.5-2.0 90 116 134 150 160 Na.sub.2 SO.sub.4 0.05 MgCl.sub.2 0.02 250 75 1.5-2.0 83 104 120 133 142 0.05 1.0-1.5 62 72 81 90 97 0.01 0.7-1.0 57 72 80 94 105 Na.sub.2 SO.sub.4 0.05 BaCl.sub.2 0.02 250 75 1.0-1.5 72 88 101 113 127 0.05 2.0-3.0 98 108 129 143 157 __________________________________________________________________________
TABLE XIV ______________________________________ Volume of Moisture Dosage of Dosage of Dosage of Filtrate Content CaCl.sub.2. Flocculant Flocculant collected of Dewatered 2H.sub.2 O I II in 20 sec. Cake (mg/l) (mg/l) (mg/l) (ml) (Wt. %) ______________________________________ 0 200 0 20 81.7 0 200 75 47 77.6 400 200 75 112 76.1 600 200 75 132 75.3 800 200 75 130 75.2 ______________________________________
TABLE XV ______________________________________ Explanation of Curves in FIGS. 6 to 8 Curves for Measurement for Dosage of Flocculant in % Vol- with resp. to SS Exfoli- ume of Mois- Symbol Flocculant Flocculant ative- Filt- ture of I* II* ness rate content Plots ______________________________________ CI 1.00% AI 0.50% A.sub.1 A.sub.2 A.sub.3 ○ CII 1.00% AI 0.50% B.sub.1 B.sub.2 B.sub.3 Δ CIII 1.00% AI 0.50% C.sub.1 C.sub.2 C.sub.3 X CIV 2.00% AI 0.50% D.sub.1 D.sub.2 D.sub.3 X CV 2.00% AV 0.70% E.sub.1 E.sub.2 E.sub.3 CVI 1.00% AI 0.50% F.sub.1 F.sub.2 F.sub.3 Δ CI 1.00% AII 0.50% G.sub.1 G.sub.2 G.sub.3 Δ CI 1.00% AII 0.50% H.sub.1 H.sub.2 H.sub.3 X CI 1.00% AIV 0.50% J.sub.1 J.sub.2 J.sub.3 ______________________________________ *See Table XVI
TABLE XVI __________________________________________________________________________ Particulars of the Flocculant Used Denota- Colloid Eq. Value tion Compound Viscosity (meq/g) __________________________________________________________________________ CI Homopolymer of dimethylaminoethyl methacrylate [η] .sup.30° C. .sub.1N--NaNO.sbsb .3 = 5.2 4.8 quaternized with methyl chloride CII Copolymer of dimethylaminoethyl methacrylate [η] .sup.30° C. .sub.1N--NaNO.sbsb .3 = 7.1 2.7 quaternized with methyl chloride and acrylamide CIII Mannich-reactioned polyacrylamide [η] .sup.30° C. .sub.1N--NaNO.sbsb .3 = 6.3 3.4 CIV Homopolymer of dimethyldiallylammonium [η] .sup.30° C. .sub.1N--NaNO.sbsb .3 = 1.4 5.8 chloride CV Polyethyleneimine (M.W. = 100,000) 18.1 CVI Acetic acid salt ofchitosan 80 cP (0.5% aq. soln.) 4.2 at 30 rpm with B-type viscometer AI Sodium salt of polyacrylic acid [η] .sup.30° C. .sub.2N--NaOH = 6.8 -10.6 AII Partially hydrolyzed polyacrylamide [ η] .sup.30° C. .sub.1N--NaNO.sbs b.3 = 18.4 -4.3 AIII Copolymer of sodium vinylsulfonate with [η] .sup.30° C. .sub.1N--NaNO.sbsb .3 = 10.2 -2.4 acrylamide AIV Terpolymer of sodium 2-acrylamido-2-methyl- [η] .sup.30° C. .sub.1N--NaNO.sbsb .3 = 16.7 -3.9 propanesulfonate, sodium acrylate and acrylamide (molar charge ratio: 2/30/68) AV Sodium carboxymethyl cellulose [η] .sup.30° C. .sub.0.1N--NaCl = 2.3 -3.2 __________________________________________________________________________
TABLE XVII ______________________________________ Explanation of Curves in FIGS. 9 and 10 Dosage of Flocculant Curves for Measurement Sym- in % with resp. to SS for bol Flocculant Flocculant Exfol. Volume of Moisture of I II Index Filtrate Content Plots ______________________________________ CVI* 0.50% AI* 0.25% K.sub.1 K.sub.2 K.sub.3 CVI 1.00% AI 0.50% L.sub.1 L.sub.2 L.sub.3 ○ CVI 3.00% AI 1.50% M.sub.1 M.sub.2 M.sub.3 □ ______________________________________ *See Table XVI
TABLE XVIII ______________________________________ Explanation of Curves in FIG. 11 Dosage of Flocculant Curves for Measurement Sym- in % with resp. to SS for bol Flocculant Flocculant Exfol. Volume of Moisture of I* II* Index Filtrate content Plots ______________________________________ AI 0.7% CI 0.5% N.sub.1 N.sub.2 N.sub.3 ○ AII 0.7% CI 0.5% P.sub.1 P.sub.2 P.sub.3 Δ AIII 0.7% CIII 0.5% Q.sub.1 Q.sub.2 Q.sub.3 X AIV 0.7% CVI 0.5% R.sub.1 R.sub.2 R.sub.3 AV 1.2% CII 0.5% S.sub.1 S.sub.2 S.sub.3 ______________________________________ *See Table XVI
TABLE XIX ______________________________________ Explanation of Curves in FIGS. 12 and 13 Average Floc-Diam. after 1st Stage Agitation (mm) 0.7 1.8 2.2 3.1 ______________________________________ FIG. 12 Suspended Solids T.sub.1 U.sub.1 V.sub.1 W.sub.1 Capture Moisture Content T.sub.2 U.sub.2 V.sub.2 W.sub.2 of Cake FIG. 13 Suspended Solids T.sub.3 U.sub.3 V.sub.3 W.sub.3 Capture Moisture content of T.sub.4 U.sub.4 V.sub.4 W.sub.4 Cake Symbol of Plots ○• ○ □ ______________________________________
TABLE XX __________________________________________________________________________ Particulars of Flocculant Used Colloid Equivalent Denotation Compound Viscosity (meq/g) __________________________________________________________________________ (I) Acetic acid salt ofchitosan 80 cP (0.5% aq. 4.2 soln.) with B-type viscometer at 30 rpm. (II) Mannich-reactioned polyacrylamide [η] .sup.30° C. .sub.1N--NaCl = 3.2 (III) A homopolymer of dimethylaminoethyl [η] .sup.30° C. .sub.1N--NaCl = 4.8 methacrylate quaternized with methyl chloride (IV) A homopolymer of dimethylaminoethyl [η] .sup.30° C. .sub.1N--NaCl = 4.8 methacrylate quaternized with methyl chloride (V) Copolymer of acrylamide and dimethyl- [η] .sup.30° C. .sub.1N--NaCl = 3.1 aminoethyl methacrylate quaternized with methyl chloride (VI) Sodium salt of polyacrylic acid [η] .sup.30° C. .sub.2N--NaOH = -10.6 (VII) Partially hydrolyzed polyacrylamide [η] .sup.30° C. .sub.1N--NaCl = -4.3 (VIII) Sodium carboxymethyl cellulose [η] .sup.30° C. .sub.0.1N--NaCl = 12.3 -3.2 __________________________________________________________________________
TABLE XXI ______________________________________ Suspended Solids Capture for the Cakes plotted in FIG. 14 Suspended Suspended Suspended Plot in Solids Plot in Solids Plot in Solids FIG. Capture FIG. Capture FIG. Capture 14 (wt. %) 14 (wt. %) 14 (wt. %) ______________________________________ A.sub.1 99 B.sub.1 99 C.sub.1 98 A.sub.2 99 B.sub.2 99 C.sub.2 95 A.sub.3 99 B.sub.3 98 C.sub.3 93 A.sub.4 99 B.sub.4 97 C.sub.4 90 A.sub.5 98 B.sub.5 93 C.sub.3 81 A.sub.6 98 A.sub.7 97 A.sub.8 97 ______________________________________
TABLE XXII ______________________________________ Suspended Solids Capture for the Cakes plotted in FIG. 15 Suspended Suspended Suspended Plot in Solids Plot in Solids Plot in Solids FIG. Capture FIG. Capture FIG. Capture 15 (wt. %) 15 (wt. %) 15 (wt. %) ______________________________________ D.sub.1 99 E.sub.1 99 F.sub.1 98 D.sub.2 99 E.sub.2 99 F.sub.2 96 D.sub.3 99 E.sub.3 98 F.sub.3 92 D.sub.4 99 E.sub.4 97 F.sub.4 83 D.sub.5 99 E.sub.5 94 ______________________________________
TABLE XXIII __________________________________________________________________________ Suspended Solids Capture for the Cakes plotted in FIG. 16 Suspended Suspended Suspended Suspended Plot in Solids Plot in Solids Plot in Solids Plot in Solids FIG. Capture FIG. Capture FIG. Capture FIG. Capture 16 (wt. %) 16 (wt. %) 16 (wt. %) 16 (wt. %) __________________________________________________________________________ G.sub.1 99 H.sub.1 99 J.sub.1 99 K.sub.1 99 G.sub.2 99 H.sub.2 99 J.sub.2 99 K.sub.2 98 G.sub.3 99 H.sub.3 99 J.sub.3 99 K.sub.3 96 G.sub.4 99 H.sub.4 99 J.sub.4 99 K.sub.4 86 __________________________________________________________________________
TABLE XXIV ______________________________________ Explanation of Curves in FIG. 17 Average Floc-Diam. after 1st Stage Agitation (mm) 0.7 1.8 2.2 3.1 ______________________________________ Suspended Solids Cap- L.sub.1 M.sub.1 N.sub.1 P.sub.1 ture Moisture Content of L.sub.2 M.sub.2 N.sub.2 P.sub.2 Cake Symbol of Plots ○• ○ □ ______________________________________
TABLE XXV __________________________________________________________________________ Particulars of the Flocculant Used Colloid Equivalent Denotation compound Viscosity (meq/g) __________________________________________________________________________ C-1 Homopolymer of dimethylaminoethyl metha- [η] .sup.30° C. .sub.1N--NaCl = 4.9 4.8 crylate quaternized with methyl chloride C-2 Copolymer of acrylamide and dimethylamino- [η] .sup.30° C. .sub.1N--NaCl = 6.1 3.1 ethyl methacrylate quaternized with methyl chloride C-3 Mannich-reaction polyacrylamide [η] .sup.30° C. .sub.1N--NaCl = 6.0 3.3 C-4 Polyethyleneimine (M.W. = 100,000) 18 C-5 Acetic acid salt ofchitosan 80 cP (0.5% aq. 4.2 siln.) with B-type viscometer at 30 rpm. A-1 Sodium polyacrylate [η] .sup.30° C. .sub.2N--NaOH = 7.2 -10.6 A-2 Partially hydrolyzed poly- [η] .sup.30° C. .sub.1N--NaCl = 19.3 -2.9 acrylamide A-3 Terpolymer of sodium 2-acrylamido-2- [η] .sup.30° C. .sub.1N--NaCl = 17.6 -3.6 methylpropanesulfonate, sodium acrylate and acrylamide (charged mole ratio: 4/26/70) __________________________________________________________________________
TABLE XXVI ______________________________________ Results of Sludge Dewatering Test Dosage Floc-Dia- of each meter after Moisture Sus- Floccu- Condi- Addition of Cont. of pended Floccu- lant tion of cationic dewatered Solids lants (both in Addi- Flocculant Cake Capture used % to SS) tion (mm) (wt. %) (wt. %) ______________________________________ C-1/A-1 0.95/0.40 I 1.7 76.4 99 II 4.2 82.4 94 C-2/A-1 0.95/0.40 I 1.7 77.8 98 II 4.6 83.6 90 C-3/A-3 0.95/0.40 I 1.5 75.6 99 II 4.0 81.3 96 C-4/A-2 2.10/0.40 I 1.1 73.5 97 II 2.7 78.4 95 C-5/A-1 0.95/0.40 I 1.3 72.0 99 II 2.2 76.3 97 ______________________________________
TABLE XXVII ______________________________________ Results of Sludge Dewatering Test Dosage Floc-Dia- for each meter after Moisture Sus- Floccu- Condi- Addition of Content of pended Floccu- lant tion of anionic dewatered Solids lants (both in Addi- Flocculant Cake Capture used % to SS) tion (mm) (wt. %) (wt. %) ______________________________________ A-1/C-1 0.75/0.56 I 1.5 75.0 99 II 3.2 80.6 94 A-2/C-3 0.75/0.56 I 1.7 76.5 99 II 5.4 82.1 92 A-1/C-5 0.75/0.56 I 1.5 73.1 99 II 3.2 77.4 96 ______________________________________
Claims (11)
Applications Claiming Priority (12)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP55108213A JPS593240B2 (en) | 1980-08-08 | 1980-08-08 | Sludge dewatering method |
JP55-108213 | 1980-08-08 | ||
JP56-11364 | 1981-01-28 | ||
JP56011364A JPS57127500A (en) | 1981-01-28 | 1981-01-28 | Flocculation treatment for sludge |
JP56015806A JPS57130599A (en) | 1981-02-06 | 1981-02-06 | Dehydration of sludge |
JP56-15806 | 1981-02-06 | ||
JP56016296A JPS57130600A (en) | 1981-02-07 | 1981-02-07 | Dehydration of sludge |
JP56-16296 | 1981-02-07 | ||
JP1686781A JPS57132509A (en) | 1981-02-09 | 1981-02-09 | Flocculation treatment of suspension |
JP56-16867 | 1981-02-09 | ||
JP56-19330 | 1981-02-12 | ||
JP56019330A JPS57135096A (en) | 1981-02-12 | 1981-02-12 | Sludge dewatering method |
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US4382864A true US4382864A (en) | 1983-05-10 |
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ID=27548333
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Application Number | Title | Priority Date | Filing Date |
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US06/287,453 Expired - Lifetime US4382864A (en) | 1980-08-08 | 1981-07-27 | Process for dewatering sludges |
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US (1) | US4382864A (en) |
DE (1) | DE3131411A1 (en) |
GB (1) | GB2082163B (en) |
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US4481115A (en) * | 1982-02-19 | 1984-11-06 | Allied Colloids Limited | Filtration of sewage sludge |
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US4759856A (en) * | 1984-04-30 | 1988-07-26 | Allied Colloids, Ltd. | Flocculation processes |
US4720346A (en) * | 1985-04-25 | 1988-01-19 | Allied Colloids Ltd. | Flocculation processes |
US4943378A (en) * | 1985-04-25 | 1990-07-24 | Allied Colloids Ltd. | Flocculation processes |
US4609470A (en) * | 1985-07-08 | 1986-09-02 | Miles Laboratories, Inc. | Method of biopolymeric sludge dewatering |
USRE36780E (en) * | 1988-12-19 | 2000-07-18 | Cytec Technology Corp. | Mannich acrylamide polymers |
USRE37037E1 (en) | 1988-12-19 | 2001-01-30 | Cytec Technology Corp. | Emulsified mannich acrylamide polymers |
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US5152896A (en) * | 1990-01-15 | 1992-10-06 | Institut Textile De France-Centre Technique Industriel | Use of grafted cellulose for purifying water |
US5158688A (en) * | 1990-03-19 | 1992-10-27 | E. I. Du Pont De Nemours And Company | Process for removing inorganic gels and incompressible solids from acidic media |
US5269939A (en) * | 1992-07-13 | 1993-12-14 | Laurent Edward L | Method of solids recovery for use in animal feed or as a fuel utilizing natural flocculents |
US5433865A (en) * | 1994-03-31 | 1995-07-18 | Laurent; Edward L. | Method for treating process waste streams by use of natural flocculants |
US6562802B2 (en) * | 1996-12-16 | 2003-05-13 | Noviscens Ab | Medical composition and uses thereof |
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Also Published As
Publication number | Publication date |
---|---|
GB2082163A (en) | 1982-03-03 |
DE3131411A1 (en) | 1982-06-24 |
GB2082163B (en) | 1983-10-26 |
DE3131411C2 (en) | 1991-05-02 |
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